Over-current protection circuits for power transistors
US4321648A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 25, 1981 |
| Grant date | Mar 23, 1982 |
| Priority date | — |
| Expiry date | Feb 25, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F1/52
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A protected transistor in an electronic circuit receives base drive current and has its collector-emitter path coupled to a source of collector-emitter potential and to a load. Overcurrent protection therefor is provided by a first, complementary conductivity type transistor connected base to emitter and emitter to base with the protected transistor, and thermally coupled thereto, to develop a collector current responsive to the collector-emitter current of the protected transistor. A comparator provides an overcurrent indication whenever the collector current of the first transistor exceeds a predetermined level. The overcurrent indication prevents further increase in the base drive current to the protected transistor. A further feature of the invention reduces the predetermined level in response to increasing collector-emitter potential of the protected transistor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.